scholarly journals Observations of the diurnal and seasonal trends in nitrogen oxides in the western Sierra Nevada

2006 ◽  
Vol 6 (12) ◽  
pp. 5321-5338 ◽  
Author(s):  
J. G. Murphy ◽  
D. A. Day ◽  
P. A. Cleary ◽  
P. J. Wooldridge ◽  
R. C. Cohen
Keyword(s):  
Nitrogen Oxides ◽  
Sierra Nevada ◽  
Thermal Dissociation ◽  
Ozone Production ◽  
Organic Nitrates ◽  
Research Station ◽  
Small Contribution ◽  
Free Troposphere ◽  
Alkyl Nitrates ◽  
Peroxy Nitrates

Abstract. Observations of speciated nitrogen oxides, namely NO2, total peroxy nitrates (ΣPNs), total alkyl nitrates (ΣANs), and HNO3 by thermal dissociation laser induced fluorescence (TD-LIF), and supporting chemical and meteorological measurements at Big Hill (1860 m), a high elevation site in California's Sierra Nevada Mountains, are described. From May through October, terrain-driven winds in the region routinely bring air from Sacramento, 100 km southwest of the site, upslope over oak and pine forests to Big Hill during the day, while at night, the site often samples clean, dry air characteristic of the free troposphere. Winter differs mainly in that the meteorology does not favour the buildup of Sacramento's pollution over the Sierra Nevada range, and the urban-influenced air that is seen has been less affected by biogenic VOC emissions, resulting in longer lifetime for NO2 and a predominance of the inorganic forms of nitrogen oxides. Summertime observations at Big Hill can be compared with those from Granite Bay, a Sacramento suburb, and from the University of California's Blodgett Forest Research Station to examine the evolution of nitrogen oxides and ozone within the urban plume. Nitrogen oxide radicals (NO and NO2), which dominate total nitrogen oxides (NOy) at Granite Bay, are rapidly converted into HNO3, ΣPNs, and ΣANs, such that these compounds contribute 29, 30, and 21% respectively to the NOy budget in the plume at Big Hill. Nevertheless, the decreasing concentrations of NO2 as the plume is advected to Big Hill lead to decreases in the production rate of HNO3 and ozone. The data also demonstrate the role that temperature plays in sequestering NO2 into peroxy nitrates, effectively decreasing the rate of ozone production. The important contribution of ΣANs to NOy in the region suggests that they should be considered with regards to export of NOy from the boundary layer. Nocturnal observations of airmasses characteristic of the free troposphere showed lower NOy concentrations, which were dominated by HNO3 with a relatively small contribution from the organic nitrates.

scholarly journals Observations of the diurnal and seasonal trends in nitrogen oxides in the western Sierra Nevada

2006 ◽  
Vol 6 (3) ◽  
pp. 4415-4464 ◽  
Author(s):  
J. G. Murphy ◽  
D. A. Day ◽  
P. A. Cleary ◽  
P. J. Wooldridge ◽  
R. C. Cohen
Keyword(s):  
Nitrogen Oxides ◽  
Sierra Nevada ◽  
Thermal Dissociation ◽  
Ozone Production ◽  
Organic Nitrates ◽  
Research Station ◽  
Small Contribution ◽  
Free Troposphere ◽  
Alkyl Nitrates ◽  
Peroxy Nitrates

Abstract. Observations of speciated nitrogen oxides, namely NO2, total peroxy nitrates (ΣPNs), total alkyl nitrates (ΣANs), and HNO3 by thermal dissociation laser induced fluorescence (TD-LIF), and supporting chemical and meteorological measurements at Big Hill (1860 m), a high elevation site in California's Sierra Nevada Mountains, are described. From May through October, terrain-driven winds in the region routinely bring air from Sacramento, 100 km southwest of the site, upslope over oak and pine forests to Big Hill during the day, while at night, the site often samples clean, dry air characteristic of the free troposphere. Winter differs mainly in that the meteorology does not favour the buildup of Sacramento's pollution over the Sierra Nevada range, and the urban-influenced air that is seen has been less affected by biogenic VOC emissions, resulting in longer lifetime for NO2 and a predominance of the inorganic forms of nitrogen oxides. Summertime observations at Big Hill can be compared with those from Granite Bay, a Sacramento suburb, and from the University of California's Blodgett Forest Research Station to examine the evolution of nitrogen oxides and ozone within the urban plume. Nitrogen oxide radicals (NO and NO2), which dominate total nitrogen oxides (NOy) at Granite Bay, are rapidly converted into HNO3, ΣPNs, and ΣANs, such that these compounds contribute 29, 30, and 21% respectively to the NOy budget in the plume at Big Hill. Nevertheless, the decreasing concentrations of NO2 as the plume is advected to Big Hill lead to decreases in the production rate of HNO3 and ozone. The data also demonstrate the role that temperature plays in sequestering NO2 into peroxy nitrates, effectively decreasing the rate of ozone production. The important contribution of ΣANs to NOy in the region suggests that they should be considered with regards to export of NOy from the boundary layer. Nocturnal observations of airmasses characteristic of the free troposphere showed lower NOy concentrations, which were dominated by HNO3 with a relatively small contribution from the organic nitrates.

scholarly journals Impact of ozone and inlet design on the detection of isoprene-derived organic nitrates by thermal dissociation cavity ring-down spectroscopy (TD-CRDS)

2021 ◽  
Author(s):  
Patrick Dewald ◽  
Raphael Dörich ◽  
Jan Schuladen ◽  
Jos Lelieveld ◽  
John N. Crowley
Keyword(s):  
Thermal Dissociation ◽  
Volume Ratio ◽  
Reaction Chamber ◽  
Organic Nitrates ◽  
Temperature Dependent ◽  
Alkyl Nitrates ◽  
Cavity Ring Down Spectroscopy ◽  
Viable Solution ◽  
Peroxy Nitrates ◽  
Cavity Ring Down

Abstract. We present measurements of isoprene-derived organic nitrates (ISOP-NITs) generated in the reaction of isoprene with the nitrate radical (NO3) in a 1 m3 Teflon reaction chamber. Detection of ISOP-NITs is achieved via their thermal dissociation to nitrogen dioxide (NO2), which is monitored by cavity ring-down spectroscopy (TD-CRDS). Using thermal dissociation inlets (TDIs) made of quartz, the temperature-dependent dissociation profiles (thermograms) of ISOP-NITs measured in the presence of ozone (O3) are broad (350 to 700 K), which contrasts the narrower profiles previously observed for e.g. isopropyl nitrate (iPN) or peroxy acetyl nitrate (PAN) under the same conditions. The shape of the thermograms varied with the TDI’s surface to volume ratio and with material of the inlet walls, providing clear evidence that ozone and quartz surfaces catalyse the dissociation of unsaturated organic nitrates leading to formation of NO2 at temperatures well below 475 K, impeding the separate detection of alkyl nitrates (ANs) and peroxy nitrates (PNs). We present a simple, viable solution to this problem and discuss the potential for interference by the thermolysis of nitric acid (HNO3), nitrous acid (HONO) and O3.

scholarly journals Day- and Night-time Formation of Organic Nitrates at a Forested Mountain-site in South West Germany

2016 ◽  
Author(s):  
Nicolas Sobanski ◽  
Jim Thieser ◽  
Jan Schuladen ◽  
Carina Sauvage ◽  
Wei Song ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
West Germany ◽  
Organic Nitrates ◽  
Lower Yield ◽  
Night Time ◽  
Alkyl Nitrates ◽  
South West ◽  
Peroxy Nitrates ◽  
Kleiner Feldberg

Abstract. We report in-situ measurement of total peroxy-nitrates (ƩPNs) and total alkyl nitrates (ƩANs) in a forested/urban location at the top of the Kleiner Feldberg mountain in South-West Germany. The data, obtained using Thermal Dissociation Cavity Ring Down Spectroscopy (TD-CRDS) in August-September 2011 (PARADE campaign) and July–August 2015 (NOTOMO campaign), represent the first detailed study of ƩPNs and ƩANs over continental Europe. We find that a significant fraction of NOx (up to 75 %) is sequestered as organics nitrates at this site. Futher, we also show that the night-time production of alkyl nitrates by reaction of NO3 with biogenic hydrocarbons is comparable to that from day-time, OH-initiated oxidation pathways. The ƩANs-to-ozone ratio obtained during PARADE was used to derive an approximate, average yield of organic nitrates at noon time from the OH initiated oxidation of VOCs of 7 % at this site in 2011, which is comparable with that obtained from an analysis of VOCs at the site. A much lower yield,

scholarly journals Day and night-time formation of organic nitrates at a forested mountain site in south-west Germany

2017 ◽  
Vol 17 (6) ◽  
pp. 4115-4130 ◽  
Author(s):  
Nicolas Sobanski ◽  
Jim Thieser ◽  
Jan Schuladen ◽  
Carina Sauvage ◽  
Wei Song ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Branching Ratio ◽  
West Germany ◽  
Organic Nitrates ◽  
Night Time ◽  
Alkyl Nitrates ◽  
South West ◽  
Peroxy Nitrates ◽  
Kleiner Feldberg

Abstract. We report in situ measurements of total peroxy nitrates (ΣPNs) and total alkyl nitrates (ΣANs) in a forested–urban location at the top of the Kleiner Feldberg mountain in south-west Germany. The data, obtained using thermal dissociation cavity ring-down spectroscopy (TD-CRDS) in August–September 2011 (PARADE campaign) and July 2015 (NOTOMO campaign), represent the first detailed study of ΣPNs and ΣANs over continental Europe. We find that a significant fraction of NOx (up to 75 %) is sequestered as organics nitrates at this site. Furthermore, we also show that the night-time production of alkyl nitrates by reaction of NO3 with biogenic hydrocarbons is comparable to that from daytime OH-initiated oxidation pathways. The ΣANs ∕ ozone ratio obtained during PARADE was used to derive an approximate average yield of organic nitrates at noon from the OH initiated oxidation of volatile organic compounds (VOCs) of  ∼  7 % at this site in 2011, which is comparable with that obtained from an analysis of VOCs measured during the campaign. A much lower AN yield,  <  2 %, was observed in 2015, which may result from sampling air with different average air mass ages and thus different degrees of breakdown of assumptions used to derive the branching ratio, but it may also reflect a seasonal change in the VOC mixture at the site.

scholarly journals Observations of total peroxy nitrates and total alkyl nitrates during the OP3 campaign: isoprene nitrate chemistry above a south-east Asian tropical rain forest

2012 ◽  
Vol 12 (2) ◽  
pp. 4797-4829
Author(s):  
E. Aruffo ◽  
P. Di Carlo ◽  
C. Dari-Salisburgo ◽  
F. Biancofiore ◽  
F. Giammaria ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Thermal Dissociation ◽  
Ozone Production ◽  
Alkyl Nitrates ◽  
Direct Excitation ◽  
Forest Sites ◽  
New Instrument ◽  
Peroxy Nitrates

Abstract. Measurements of total peroxy nitrates (ΣRO2NO2, ΣPNs), total alkyl nitrates (ΣRONO2, ΣANs) and nitrogen dioxide (NO2) were made above the surface of a Malaysian tropical rain forest in Borneo, using a laser-induced fluorescence instrument developed at the University of L'Aquila (Italy). This new instrument uses the direct excitation of NO2 at 532 nm in order to measure its concentrations detecting by the NO2 fluorescence at wavelengths longer than 610 nm. ΣPNs and ΣANs are indirectly measured after their thermal dissociation into NO2. Observations showed enhanced levels of NO2 during nighttime, an increase of ΣPNs during the afternoon and almost no evident diurnal cycle of ΣANs. The diurnal maximums of 200 pptv for ΣPNs and ΣANs are well below the peaks reported in other forest sites. A box model constrained with measured species, reproduces well the observed ΣPNs, but overestimates ΣANs concentrations. The reason of this model-observation discrepancy could be a wrong parameterization in the isoprene nitrates (INs) chemistry mechanism. Sensitivity tests show that: (1) reducing the yield of INs from the reaction of peroxy nitrates with NO to almost the lowest values reported in literature (5%), (2) reducing the INs recycling to 70% and (3) keeping the INs dry deposition at 4 cm s−1, improve the agreement between modelled and measured ΣANs of 20% on average. These results imply that in the tropical rain forest, even if ΣPNs and ΣANs concentrations are lower than those observed in other North American forests, the yield and dry deposition of INs are similar. Another comparable result is that in the INs oxidation its recycling dominates with only a 30% release of NO2, which has implications on tropospheric ozone production and aerosol budget.

scholarly journals A thermal-dissociation–cavity ring-down spectrometer (TD-CRDS) for the detection of organic nitrates in gas and particle phases

2020 ◽  
Vol 13 (11) ◽  
pp. 6255-6269
Author(s):  
Natalie I. Keehan ◽  
Bellamy Brownwood ◽  
Andrey Marsavin ◽  
Douglas A. Day ◽  
Juliane L. Fry
Keyword(s):  
Thermal Dissociation ◽  
Organic Nitrates ◽  
Alkyl Nitrates ◽  
Aerosol Mass Spectrometer ◽  
Particle Measurements ◽  
Aerosol Mass ◽  
Oxidant Concentration ◽  
Peroxy Nitrates ◽  
Concentration Chamber ◽  
Cavity Ring Down

Abstract. A thermal-dissociation–cavity ring-down spectrometer (TD-CRDS) was developed to measure NO2, peroxy nitrates (PNs), alkyl nitrates (ANs), and HNO3 in the gas and particle phase, built using a commercial Los Gatos Research NO2 analyzer. The detection limit of the TD-CRDS is 0.66 ppb for ANs, PNs, and HNO3 and 0.48 ppb for NO2. For all four classes of NOy, the time resolution for separate gas and particle measurements is 8 min, and for total gas + particle measurements it is 3 min. The accuracy of the TD-CRDS was tested by comparison of NO2 measurements with a chemiluminescent NOx monitor and aerosol-phase ANs with an aerosol mass spectrometer (AMS). N2O5 causes significant interference in the PN and AN channel under high oxidant concentration chamber conditions, and ozone pyrolysis causes a negative interference in the HNO3 channel. Both interferences can be quantified and corrected for but must be considered when using TD techniques for measurements of organic nitrates. This instrument has been successfully deployed for chamber measurements at widely varying concentrations, as well as ambient measurements of NOy.

scholarly journals Impact of ozone and inlet design on the quantification of isoprene-derived organic nitrates by thermal dissociation cavity ring-down spectroscopy (TD-CRDS)

2021 ◽  
Vol 14 (8) ◽  
pp. 5501-5519
Author(s):  
Patrick Dewald ◽  
Raphael Dörich ◽  
Jan Schuladen ◽  
Jos Lelieveld ◽  
John N. Crowley
Keyword(s):  
Thermal Dissociation ◽  
Volume Ratio ◽  
Reaction Chamber ◽  
Organic Nitrates ◽  
Temperature Dependent ◽  
Alkyl Nitrates ◽  
Cavity Ring Down Spectroscopy ◽  
Reactive Material ◽  
Peroxy Nitrates ◽  
Cavity Ring Down

Abstract. We present measurements of isoprene-derived organic nitrates (ISOP-NITs) generated in the reaction of isoprene with the nitrate radical (NO3) in a 1 m3 Teflon reaction chamber. Detection of ISOP-NITs is achieved via their thermal dissociation to nitrogen dioxide (NO2), which is monitored by cavity ring-down spectroscopy (TD-CRDS). Using thermal dissociation inlets (TDIs) made of quartz, the temperature-dependent dissociation profiles (thermograms) of ISOP-NITs measured in the presence of ozone (O3) are broad (350 to 700 K), which contrasts the narrower profiles previously observed for, for example, isopropyl nitrate (iPN) or peroxy acetyl nitrate (PAN) under the same conditions. The shape of the thermograms varied with the TDI's surface-to-volume ratio and with material of the inlet walls, providing clear evidence that ozone and quartz surfaces catalyse the dissociation of unsaturated organic nitrates leading to formation of NO2 at temperatures well below 475 K, impeding the separate detection of alkyl nitrates (ANs) and peroxy nitrates (PNs). The use of a TDI consisting of a non-reactive material suppresses the conversion of isoprene-derived ANs at 473 K, thus allowing selective detection of PNs. The potential for interference by the thermolysis of nitric acid (HNO3), nitrous acid (HONO) and O3 is assessed.

scholarly journals Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub>, and RONO<sub>2</sub> in the atmosphere

2021 ◽  
Vol 14 (6) ◽  
pp. 4033-4051
Author(s):  
Chunmeng Li ◽  
Haichao Wang ◽  
Xiaorui Chen ◽  
Tianyu Zhai ◽  
Shiyi Chen ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Lookup Table ◽  
Organic Nitrates ◽  
Peroxy Radicals ◽  
Alkyl Nitrates ◽  
Mixing Ratios ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Peroxy Nitrates ◽  
Field Deployment

Abstract. We developed thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS) for the in situ measurement of NO2, total peroxy nitrates (PNs, RO2NO2), and total alkyl nitrates (ANs, RONO2) in the atmosphere. PNs and ANs were thermally converted to NO2 at the corresponding pyrolytic temperatures and detected by CEAS at 435–455 nm. The instrument sampled sequentially from three channels at ambient temperature, 453 and 653 K, with a cycle of 3 min, to measure NO2, NO2+ PNs, and NO2+ PNs + ANs. The absorptions between the three channels were used to derive the mixing ratios of PNs and ANs by spectral fitting. The detection limit (LOD, 1σ) for retrieving NO2 was 97 parts per trillion by volume (pptv) in 6 s. The measurement uncertainty of NO2 was 9 %, while the uncertainties of PN and AN detection were larger than those of NO2 due to chemical interferences that occurred in the heated channels, such as the reaction of NO (or NO2) with the peroxy radicals produced by the thermal dissociation of organic nitrates. Based on laboratory experiments and numerical simulations, we created a lookup table method to correct these interferences in PN and AN channels under various ambient organic nitrates, NO, and NO2. Finally, we present the first field deployment and compare it with other instruments during a field campaign in China. The advantages and limitations of this instrument are outlined.

scholarly journals Observations of the effects of temperature on atmospheric HNO<sub>3</sub>, ΣANs, ΣPNs, and NO<sub>x</sub>: evidence for a temperature-dependent HO<sub>x</sub> source

2008 ◽  
Vol 8 (6) ◽  
pp. 1867-1879 ◽  
Author(s):  
D. A. Day ◽  
P. J. Wooldridge ◽  
R. C. Cohen
Keyword(s):  
Sierra Nevada ◽  
Western Slope ◽  
Oxides Of Nitrogen ◽  
Temperature Dependent ◽  
Alkyl Nitrates ◽  
Temperature Trends ◽  
Sierra Nevada Mountains ◽  
Peroxy Nitrates ◽  
Effects Of Temperature ◽  
Increasing Temperature

Abstract. We describe observations of atmospheric reactive nitrogen compounds including NO, NO2, total peroxy nitrates, total alkyl nitrates, and HNO3 and their correlation with temperature. The measurements were made at a rural location 1315 m a.s.l. on the western slope of the Sierra Nevada Mountains in California during summer of 2001. The ratio of HNO3 to its source molecule, NO2, and the ratio of HNO3 to all other higher oxides of nitrogen (NOz) both increase with increasing temperature. Analysis of these increases suggests they are due to a steep increase in OH of between a factor of 2 and 3 over the range 18–32°C. Total peroxy nitrates decrease and total alkyl nitrates increase over the same temperature range. The decrease in the total peroxy nitrates is shown to be much less than expected if the rate of thermal decomposition were the sole important factor. This observation is consistent with the increase in OH inferred from the temperature trends in the HNO3/NO2 ratio.

scholarly journals Observations of HNO<sub>3</sub>, ΣAN, ΣPN and NO<sub>2</sub> fluxes: evidence for rapid HO<sub>x</sub> chemistry within a pine forest canopy

2007 ◽  
Vol 7 (3) ◽  
pp. 7087-7136 ◽  
Author(s):  
D. K. Farmer ◽  
R. C. Cohen
Keyword(s):  
Nitrogen Oxides ◽  
Sierra Nevada ◽  
Residence Time ◽  
Ponderosa Pine ◽  
Forest Canopy ◽  
Similarity Theory ◽  
Peroxy Radical ◽  
Pine Forest ◽  
Alkyl Nitrates ◽  
Emission Fluxes

Abstract. Measurements of exchange of reactive nitrogen oxides between the atmosphere and a ponderosa pine forest in the Sierra Nevada Mountains are reported. During winter, we observe upward fluxes of NO2, and downward fluxes of total peroxy and peroxy acyl nitrates (ΣPNs), total gas and particle phase alkyl and multifunctional alkyl nitrates (ΣANs(g+p), and the sum of gaseous HNO3 and semi-volatile NO3− particles (HNO3(g+p). We use calculations of the vertical profile and flux of NO, partially constrained by observations, to show that net midday ΣNOyi fluxes in winter are –4.9 ppt m s−1. The signs and magnitudes of these wintertime individual and ΣNOyi fluxes are in the range of prior measurements. In contrast, during summer, we observe downward fluxes only of ΣANs(g+p), and upward fluxes of HNO3(g+p), ΣPNs and NO2 with signs and magnitudes that are unlike most, if not all, previous observations and analyses of fluxes of individual nitrogen oxides. The results imply that the mechanisms contributing to NOy fluxes, at least at this site, are much more complex than previously recognized. We show that the observations of upward fluxes of HNO3(g+p) and ΣPNs during summer are consistent with oxidation of NO2 and acetaldehyde by OH with the product of concentration and residence time equal to 1.1×1010 molec OH cm−3 s, e.g. 3×107 molecules cm−3 OH for a 400 s canopy residence time. We show that ΣAN(g+p) fluxes are consistent with this same OH if the reaction of OH with ΣANs produces either HNO3 or NO2 in 6–30% yield. Calculations of NO fluxes constrained by the NO2 observations and the inferred OH indicate that NOx fluxes are downward into the canopy because of the substantial conversion of NOx to HNO3 and ΣPNs in the canopy. Even so, we derive that NOx emission fluxes of ~15 ng(N) m−2 s−1 at midday during summer are required to balance the NOx and NOy flux budgets. These fluxes are partly explained by estimates of soil emissions (estimated to be between 3 and 6 ng(N) m−2 s−1). One possibility for the remainder of the NOx source is large HONO emissions. Alternatively, the 15 ng(N) m−2 s−1 emission estimate may be too large, and the budget balanced if the deposition of HNO3 and ΣPNs is slower than we estimate, if there are large errors in either our understanding of peroxy radical chemistry, or our assumptions that the budget is required to balance because the fluxes do not obey similarity theory.

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